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Smiling lowers heart rate, relieves stress, research finds

July 31, 2012
Courtesy of the Association for Psychological Science
and World Science staff

Just grin and bear it! At some point, we have all probably heard or thought some­thing like this when fac­ing a tough situa­t­ion. But is there any truth to the ad­vice? Feel­ing good usu­ally makes us smile, but does it work the oth­er way around? Can smil­ing ac­tu­ally make us feel bet­ter?

A new study sug­gests the an­swer is yes. Tara Kraft and Sar­ah Press­man of the Uni­vers­ity of Kan­sas in­ves­t­i­gated how dif­fer­ent types of smil­ing, and aware­ness of smil­ing, af­fects our abil­ity to re­cov­er from stress.

“Age old adages, such as ‘grin and bear it’ have sug­gested smil­ing to be not only an im­por­tant non­ver­bal in­di­ca­tor of hap­pi­ness but al­so wish­fully pro­motes smil­ing as a pan­a­cea for life’s stress­ful events,” said Kraft. “We wanted to ex­am­ine wheth­er these adages had sci­en­tif­ic mer­it; wheth­er smil­ing could have real health-relevant ben­e­fits.”

The find­ings are to ap­pear in the re­search jour­nal Psy­cho­log­i­cal Sci­ence.

Smiles are of­ten di­vid­ed in­to two types: stand­ard smiles, which use the mus­cles sur­round­ing the mouth, and gen­u­ine or Duchenne smiles, which en­gage the mus­cles sur­round­ing both the mouth and eyes. Pre­vi­ous re­search has found that pos­i­tive emo­tions can help dur­ing times of stress and that smil­ing can af­fect emo­tion. But Kraft and Press­man’s work is billed as the first of its kind to ex­pe­ri­men­tally ma­ni­pu­late the types of smiles peo­ple make to as­sess the ef­fects of smil­ing.

The re­search­ers re­cruited 169 par­ti­ci­pants from a Mid­west­ern uni­vers­ity. The study in­volved two phases: train­ing and test­ing. Dur­ing the train­ing phase, par­ti­ci­pants were di­vid­ed in­to three groups, and each was trained to hold a dif­fer­ent fa­cial ex­pres­sion. Par­ti­ci­pants were in­structed to hold chop­sticks in their mouths in such a way that they en­gaged fa­cial mus­cles used to cre­ate a neu­tral fa­cial ex­pres­sion, a stand­ard smile, or a Duchenne smile. The chop­sticks were the key be­cause they forced peo­ple to smile with­out be­ing aware that they were do­ing so: only half of the group mem­bers were ac­tu­ally told to smile.

For the test­ing phase, par­ti­ci­pants were asked to work on mul­ti­task­ing ac­ti­vi­ties. What the par­ti­ci­pants did­n’t know was that the mul­ti­task­ing ac­ti­vi­ties were de­signed to be stress­ful. The first stress-inducing ac­ti­vity re­quired the par­ti­ci­pants to trace a star with their non-dominant hand by look­ing at a re­flec­tion of the star in a mir­ror. The sec­ond stress-inducing ac­ti­vity re­quired par­ti­ci­pants to sub­merge a hand in ice wa­ter.

Dur­ing both tasks, par­ti­ci­pants held the chop­sticks in their mouth as they were taught in train­ing. The re­search­ers meas­ured par­ti­ci­pants’ heart rates and self-re­ported stress lev­els.

Com­pared to par­ti­ci­pants who held neu­tral ex­pres­sions, par­ti­ci­pants who were in­structed to smile, and in par­tic­u­lar those with Duchenne smiles, had low­er heart rate lev­els af­ter re­cov­ery from the stress, the in­ves­ti­ga­tors found. Those who held chop­sticks in a way that forced them to smile, but were not ex­plic­itly told to smile as part of the train­ing, al­so re­ported a smaller de­crease in pos­i­tive emo­tions com­pared to those who held neu­tral ex­pres­sions.

“The next time you are stuck in traf­fic or are ex­periencing some oth­er type of stress,” said Press­man, “you might try to hold your face in a smile for a mo­ment. Not only will it help you ‘grin and bear it’ psy­cho­log­ic­ally, but it might ac­tu­ally help your heart health as well!”


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Just grin and bear it! At some point, we have all probably heard or thought something like this when facing a tough situation. But is there any truth to the advice? Feeling good usually makes us smile, but does it work the other way around? Can smiling actually make us feel better? A new study suggests the answer is yes. Tara Kraft and Sarah Pressman of the University of Kansas investigated how different types of smiling, and awareness of smiling, affects individuals’ ability to recover from stress. “Age old adages, such as ‘grin and bear it’ have suggested smiling to be not only an important nonverbal indicator of happiness but also wishfully promotes smiling as a panacea for life’s stressful events,” said Kraft. “We wanted to examine whether these adages had scientific merit; whether smiling could have real health-relevant benefits.” The findings are to appear in the research journal Psychological Science. Smiles are often divided into two types: standard smiles, which use the muscles surrounding the mouth, and genuine or Duchenne smiles, which engage the muscles surrounding both the mouth and eyes. Previous research has found that positive emotions can help during times of stress and that smiling can affect emotion. Kraft and Pressman’s work is billed as the first of its kind to experimentally manipulate the types of smiles people make to assess the effects of smiling. The researchers recruited 169 participants from a Midwestern university. The study involved two phases: training and testing. During the training phase, participants were divided into three groups, and each was trained to hold a different facial expression. Participants were instructed to hold chopsticks in their mouths in such a way that they engaged facial muscles used to create a neutral facial expression, a standard smile, or a Duchenne smile. The chopsticks were the key because they forced people to smile without being aware that they were doing so: only half of the group members were actually instructed to smile. For the testing phase, participants were asked to work on multitasking activities. What the participants didn’t know was that the multitasking activities were designed to be stressful. The first stress-inducing activity required the participants to trace a star with their non-dominant hand by looking at a reflection of the star in a mirror. The second stress-inducing activity required participants to submerge a hand in ice water. During both of the stressful tasks, participants held the chopsticks in their mouth just as they were taught in training. The researchers measured participants’ heart rates and self-reported stress levels throughout the testing phase. Compared to participants who held neutral expressions, participants who were instructed to smile, and in particular those with Duchenne smiles, had lower heart rate levels after recovery from the stressful activities, the investigators found. Participants who held chopsticks in a manner that forced them to smile, but were not explicitly told to smile as part of the training, also reported a smaller decrease in positive emotions compared to those who held neutral facial expressions. “The next time you are stuck in traffic or are experiencing some other type of stress,” said Pressman, “you might try to hold your face in a smile for a moment. Not only will it help you ‘grin and bear it’ psychologically, but it might actually help your heart health as well!”